Low density parity check (LDPC) code is a type of linear block code including a sparse check matrix, and is characterized by a flexible structure and low decoding complexity. Because decoding the LDPC code uses a partially parallel iterative decoding algorithm, the LDPC code has a higher throughput than a conventional turbo code. The LDPC code may be used as an error-correcting code in a communication system, so as to increase channel transmission reliability and power utilization. LDPC code may further be widely applied to space communication, fiber optic communication, a personal communication system, an asymmetric digital subscriber line (ADSL), a magnetic recording device, and the like. The LDPC code scheme has been currently considered as one of channel coding schemes in the fifth generation mobile communication systems.
In practical applications, LDPC matrices characterized by different special structures may be used. An LDPC matrix H, having a special structure, may be obtained by expanding an LDPC base matrix having a quasi cyclic (QC) structure.
Generally, lengths of to-be-encoded information bit sequences vary from tens to hundreds of bits, and code rates required by a communication system are also flexibly variable. How to support encoding on information bit sequences of various lengths, to satisfy code rate requirements of a system becomes a problem that needs to be resolved.